Multitray clarification



March 7, 1944. w. c. WEBER I MULTI RAY CLARIFICATION 1941 2 Sheets-Sheet 1 Filed Aug. 25

2. I ATTORNEY arch 1944.. w. c. WEBER ,343,836 MULTITRAY CLARIFICATION Filed Aug. '25, 1941 2 Sheets-Sheet 2 Patented Mar. 7, 1944 STATESPATEN FElCE MULTITRAY CATION William G. Weber, Westport, Conn., The Don- Company, New York, N.

tion of Delaware casino!- to 1., a corpora- Application August 25, 1941, Serial No. 408,219

11 Claims.

the production of cane and beet sugar.

More specifically, the object of the present invention is to increase the solids thickening capacity, relative to the sedimentation and clarified liquid removal capacity, of a multitray clarifler adapted for use in accordance with the method disclosed and claimed in the Rolston Patent 2,195,739 of April 2, 1940, and having separate feed and solids discharge. channels formed in the central column portion of the rotating structure which support the mud rakes in the different clarifler compartments, in the general manner disclosed and claimed in Patent 2,253,543 of August 30, 1941, granted on an application flied jointly by William E. Geissler and me on August The method of the above-mentioned Rlolston patent is characterized primarily by the supply of liquid to the diiferent superposed compartments of the multitray clarifler and the removal of settled solids, commonly called "mu from the said compartments through separate flow paths, in suchmanner that the amount of liquid fed to and clarified in each of said compartments may be controlled by regulating the rate of outflow of clarified liquid from the compartment.

The above-mentioned Weber and Geissler application discloses a multi-tray clarifler especially devised for use in "the practice of the Rolston method, and characterized by its provisions for feeding liquid to be clarified to the different clarifying compartments from a superposed conditioning or flocculation chamber, through a feed channel or channels formed in the central column portion of the rotating structure supporting the mud rakes provided in the different compartments to work the solids settling therein through outlets opening to a solids discharge channel or channels also formed in said central column. The solids separated from'the clarified liquid in each upper clarifying compartment are discharged into the lowermost clarifying compartment in which the solids are subjected to a thick,- ening action which maybe wholly due to suitably prolonged subsidence or may be due in part to subsidence and in part to the action of thickening elements carried by the rotating structure.

- liquid in said chambers,-and in other compartin the compartment The primary objectand effect of the Rolston method is to increase theolarifying capacity of the lower clarifying compartments relative to the uppermost clarifying compartment of a multitray clarifler and thereby to increase the overall clarifying capacity of a clarifler of given bulk. A further increase in the clarifying capacity of a multitray clarifler constructed and operated in accordance with the disclosure of the Weber and Geissler application is obtainable through the effective flocculation which may be effected in the upper flocculation chamber of such a clarifler,

coupled with capacity of the clarifier to pass the flocculated liquid from said chamber to the subjacent clarifying compartments. with little disintegration of the larger flocs formed in the flocculating chamber.

In the conjoint use of the inventions disclosed and claimed in the above-mentioned Rolston patcut and in the Weber and Geissler application, it has been found that a multitray clarifler including four or more superposed clarifying compartments will separate more solids from the liquid undergoing clarification than can be suitably thickened preparatory to their removal from the clarifler in the single bottom thickening com partment of such a clarifler as is shown in the Rolston patent or Webertion.

In accordance with the present invention, I increase the solids thickening capacity of a multitray clarifler by providing special solids thickening means in at least two of the superposed compartments which serve as thickening chambers for thickening solids separated from the clarified ments respectively above the thickening chambers and serving as preliminary sedimentation chambers.

In a preferred form of the present invention means are provided for separately withdrawing from each thickening chamber of the clarifler solids thickened therein. In this form of the invention each of the thickening chambers advantageously receive sedimented solids from one or more immediately adjacent preliminary Bedlmentation chambers above the thickening chamber.

In another desirable form of the present invention solids are allowed to accumulate and are subiectod to the action of special thickening means immediately above the bottom-compartment of the clarlfler, as well as in said bottom compartment, both ments thusserving as thickening chambers. In

and Geissler applicaof said com-partmy invention are descriptive matter in which described preferred improvem invention.

supported bythe the last mentioned form solids thickened in the ing chambers are passed into the lowerv thickening chamber and means are rovided for discharging from the last mentioned chamber all of the solids'sedimented and thickened in the-clarifler.

Various features of novelty which characterize pointedout with particularity in the claims annexed to and forming a part of this specification. For a better understandin of the invention, however, its advantages and specific object attainedwlth its use, reference should be had to the accompanying drawings and I have illustrated and ts of the present of the invention, the

Of the drawings:

Fig-1 is'a somewhat diagrammatic plan view of one form of my improved clarifler; Fig. 2 is a vertical section on the line 22 of Fig. 1; Fig. 2A is a diagrammatic elevation on a difierent plane of a portion of the apparatus shown in Fig. 2; Fig. 3 isan enlarged reproduction of a portion of Fig. 2; and Fig. 4 is a somewhat diagrammatic sectional elevation of a clarifier embodying a modifled form of the present invention.

In'the'drawings and referring first to the form of the invention shown in F1 s. 1 and 2, l desig nates a substantially round 11 tanding tank having a bottom ll, preferably somewhat dished so as to slope toward the center, and having a top wall or cover l2, as iscustomarily desirable when the clarifier is used in the clarification of hot sugar juice. A scum chamber l3. extends upwardly from the cover l2 and is in open communication' through the latter with the uppermost compartment A of the tank. A closed launder or conduit l4, receives scum rising in the chamber l3 and passing over a weir i5, and conducts the scum toward a point of ultimate disposal. v Spaced above the scum chamber l3, and supported from the tank top l2 by suitable legs I6, is a. bridge or platform structure comprising horizontal beams l1 and transversely extending beams l8. Said platform structure supports actuating means comprising a motor is, power transmission mechanism and stationary bearing means 2!, for a. rotating structure which is rotatably supported by said bearing means and comprises a central column 22 and mud rakes 23,

central column.

thetank I0 is divided by a The interior of series of substantially horizontal dished trays or partitions 24, into a plurality of superposed compartments, comprising an upper flocculating compartment or feed chamber A, and suhi acent-compartments, B, C, D and E. In each of the latter a substantial amount of sedimentation occurs in the normal contemplated use of the clarifler.

-Mud rakes 23 are prdvidedin each of. the differalthoush V 'ent compartments A, B, 'C,'D and E. only a relatively; smallv amount of sedimentation is effected in the flocculation compartment A in normal operation. The mud rakes 23 in each compartment work the portion of the com ent toward a solids outlet at the center or the compartment. ,As the mud rakes may be of any usual or suitable form, further description thereoi is unnecessary herein.

Arms 25 above the mud rakes 23' in the compartment A, support uprising flocculation blades or'paddles 2i,

from the axis of the rotating structure; The ud' solids settling in the lower upper of the two thicken- I rakes '23 in the bottom compartment E, support ele-f and give motion to special mud thickening ments in the tom of blades or pickets 21 each secured at its lower end to and extending up ward vertically from the corresponding 'mud rake arm 23. Similar specialmudthickening elements or pickets 21 are supported by and extend upward from the mud rake arms 23 in compartment C which is separated from the bottom compartment E by the intervening compartment D.

' As shown, the liquid to be clarified is introduced into the. fiocculating compartment A through a nozzle 30, adjacent and tangential to the periphthe bottom level 'of the eral wall of the compartment. Advantageously the nozzle 30 is arranged to discharge the feed into the compartment A in a tangential direction opposite to the movement of the tips. of the flocculation arms 25 and in such a manner that the velocity of liquid flow relative to paddles 26 may be of the order of 1.5 feet per second, in accordance with the invention of my prior application, 347,837, filed July 27, 1940, notwithstanding the relatively slow angular movement of the rotating structure desirable for mud raking purses.

The central column 22 is hollow and comprises a body portion in the form of .the metallic tube or pipe to which the mud rake and flocculating arms are attached. The tube or column wall is formed with a plurality of feed inlet ports 3| located at difierent levels a ove the bottom wall of the compartment A, through which feed liquid passes from the compartment A into the bore or hollow interior is also formed with mud inlet ports 33 adjacent central portion of compartment A, through which the small amount of mud settling out of the liquid in the compartfeed outlet openings arranged at diflerent dis ces the compartment 3 passes A along a flow path attached at its upper ment A' passes into ".the feed channel 32, and thence, under the action of gravity, into the compartment E. The quantity of mud passing into the feed channel 32 through the ports 83 is too small to be practically objectionable. The provision of the mud outlet ports 33 for the compartment A in the central column wall, makes it possible to provide a mud seal between the centre column and the margin of the central opening in the partition 24 between the compartments A and B and thereby avoid into the compartment B from the compartment in which flees in the feed liquid might be subjected to objectionable disintegration.

.The said means for forming the said mud seal between the compartments A and B comprises an annular flange 36 carried by and extending radially away from the central column 22 and having its peripheral edge upturned to form a seal chamber into which extendsa depending flange or boot portion 85 of the partition 24 at the periphery of the central opening in the latter.

.The centralfeed. channel 32 is formed with 36 in its wall, which open to the compartment B thereonand within the receiving chamber surrounded by cylindricalflange 31. The latter is end to the top wall of the compartment B, and is open at its lower end to said compartment about half way between the adjacent portions-oithe topand bottom walls or the compartment, and is considerably larger in diameter than the feed channel 32. v

The solids or mud settling out i the liquid in through central open- 32 of the column. The tube wall leakage of feed liquid in' the upper central portion ing in the bottom wall of the latter into the sub- .iacent compartment through an annular mud channel which surrounds the tubular body portion of the'central column 22 and is surrounded by a tubular member 33 which is supported from the tubular body of the central columnby feed tubes 39, each of which is secured at one end .to,

and extend radially away from the central 001- umn body. The tubes 39 are open at their inner ends to the feed channel 32 in the column 22, and open at their outer ends into a corresponding .feed receiving chamber surrounded by a cylindrical flange 31,

cylindrical flange 31, depending from the partition 24 between the compartments 0 and D. The inner wall of the trough 4| is formed by the lower conical portion of a. member 42 which ha its lower, large diameter end within and secured to the surrounding flange part 31. The upper portion of the member 42 is cylindrical and'has an internal diameter slightly larger than the external diameter of the tubular body portion of-the column 22. portion ofthe member 42 extends into an annular pocket open at its lower end and formed by a hood member 43. The latter is carried by the central column body 22 and comprises a flange The upper end of the cylindrical extending radially away from the body 22 and a depending cylindrical portion surrounding and spaced away from the upper end portion of the part 42. Mud scraper arms secured to and depending from-the hood member 43, extend into and comprise scraper portions alongside the side walls of the trough. The means shown for withdrawing mud from the mud trough 4| comprises a separate mud outlet pipe 44 extending radially away from the outer wall of the mud pocket to and through the tank wall "L.

Liquid to be clarified is fed into the compartment D through outlet openings '36 in thewall oi the central feed channel 32, which are similar in form and disposition to those through which the compartment B is fed. Mud worked to'the centre oithe lower portion of the compartment D passes into the lowermost compartment E through an annular mud channel between the 3 outlet pipe 41. The latter is shown as connected by uprising pipe sections 48 and 43 to one inlet of the customary duplex mud pump 50. The

latter has a second inlet connected through a pipe section 5| and valve 52 .to the outer end of the pipe 44 through which mud is discharged from the compartment 0.

As shown, the mud pump has outlet pipes opening into the launder l4 and the latter communicates with a discharge pipe 59 extending downwardly below the pump 50.

Each of the compartments B, C, D and E serves as a. clarifying compartment and is provided with a corresponding clarified Juice outlet pipe 56 shown as communicating externally of the tank .l0 with a clarified liquid overflow box 51 which may be formed in the usual manner and comprises provisions of the usual form for independently regulating the amounts of clarified liquid withdrawn from the difierent clarifying compartments, and includes a clarified juice outlet 58.

The general operation of the apparatus shown in Figs. land 2 will be readily apparent to those familiar with the operation of prior multl-tray clarifiers employed in the clarification of sugar juices and for analogous purposes.

The' relative portions of t e liquid entering the compartment A through the tangential feed nozzle 30 which are passed to and clarified in the different clarifying compartments, may be regulated by the adjustment of the clarified liquid outflow provisions in the clarifying liquid overflow box 51, exactly as in any multi-tray clarifler heretofore operated in accordance with the methcane 0d of the Rolston patent. As will be apparent, the distribution of feed among the diiferent com-r partments A, B, C, D and E, will not be modified or afiected by the provisions disclosed for normally thickening in and discharging from the compartment C all of the mud settling out of the liquid inthat compartment or received there- I in from the compartment B. In the normal operation of the clarifler arrangement shown in Figs. 1-3, approximately one-half of .the solids separated from the liquid clarified is thickened in and discharged from the compartment C.

drical member38, as mud passes into the compartment C from the compartment B. The cylindrical member 38 in the compartment .E is supported by radial feed tubes 33 in communication with the feed channel 32 which open at their outer ends into a feed chamber surrounded by a cylindrical member "connected at upper end to top wall 24 of compartment E, all arranged as arethe feed provisions for the compartment C.

-As shown, the feed channel 32 in the hollow column body 22 is open at its lower end to the compartment E at a level somewhat below that of the tops 01 the mud thickening pickets 21. At

its lower end the central column supports in-.

At its lower end said conical mud outlet portion 43 is connected. in the usual manner to a horizontally disposed mud The mud thickening capacity of the clarifler is thus approximately double what it would be if.

all of the solids were thickened in the bottom compartment E. In consequence the mud thick-v ening and discharge capacity of the clarifler, is ample to permit operation of the clarifler at its maximum sedimentation capacity. The invention thus gives the practical advantage and result of a substantial increase in the overall capacity of the clarifler.

It is particularly to be noted that the provisio of the special mud thickening means for, and a separate mud draw-ofi connection to, each of a plurality of the clarifying compartments, makes it practically possible to thicken and remove the settled solids or muds at substantially the same rate at which the solids are settled. As a result of this, the clarifying capacity of the different compartments need not be impaired by objectionably large mud accumulations therein, and it is practically possible to avoid detrimental results of prolonged retention of stagnant solids in a sedimentation space-which in the clarification of cane sugar Juice causes inversion and fermentation.

The modified embodiment of the invention shown somewhat diagrammatically in Fig. 4, is

similar inmost of its features to the clarifler vided with a mud takeofl tray, and is,

' bottom mud outlet cone 46. The tube 60,

not the .er than generally similar the upper train 24.

' dinarllyresults from the .loadonthe compartments B and C is undesirshown in Figs. 1-3. In the drawings, corresponding parts of the two clarifiers'which present construction first described, in that in includes no special mud thickening means and is not proin fact, a replica of the compartments and D. In Fig. 4 each of the compartments A, B, CA and D, is in communication with the immediate sub-.

iacent compartment B, CA, Dand EA, respec tively, through a corresponding annular mud channel section formed by a cylindrical member ll surrounding and spaced away from the central column body tube 22A, and in telescopic relation with the boot 35 depending from and surrounding the central opening in the partition 24 above the compartment, each such mudchannei section is similar in form and construction to the mud channel section connecting the compartments B and C of the construction first described.

In Fig. 4, the feed to each'oi the compartments 13, CA, D and EA from the flocculation chamber A, is through the central column feed channel 32A and the radial pipes 39 supporting the corresponding cylindrical member 38, but in normal contemplated operation of the .clarifier shown in Fig. 4, there is no direct feed of clarified liquid partment C space in the into the botiomcompartment F from the central column feed channel 32A. As shown, the central column tubular body terminates within the compartment EAand has its lower end closed except for an axial tubular extension 60 of much smaller diameter which extends down to the level of the which is open at its ends, is adapted to pass any sand or other solids settling out of the'liquid in the feed channel 22A into admixture with the mud being thickened in and ment F. bottom cone scrapers 45 and extends through a bearing bracket 8| secured for the central columnassembly.

The compartment EA' of Fig. 4 rake and mud thickening means like" those in the bottom compartment E' of Fig. 2 and d1f1 iers from the latteressentially only in that it is lowermost or the clarifler and discharges mud into the subiacent compartment F through a central opening in-the tray 24 between the compartments and includes mud I subiacent compartments D and E. The mud overflow into the compartment D from the comunder such circumstances, effects a temporary improvement in the load distribution andminimizes the tendency of the mud accumulation in the compartment 0 to interfere with the. 7

regular operation of that compartment.

The lower compartment EA of Fig. 4 includes mud rakes 23 carrying thickening pickets 21 and. connected to and rotated by the tubular portion 60 of the central column, which may be similar in construction and operation to the mud rake and thickening means in the bottom compartment E of the'clarifier shown in Fig. 2. The compartment]? of Fig. 4 is provided with a clarified juice drawofl! piping "for the removal'of clarified liquid accumulating in the upper portion of the compartment, since considerable amounts of clarified liquid will separate from the solids and liquid mixture entering the compartment F, largely as a result of subsidence and partly due to the action of the mud rake and thickenin means therein in releasing and providing upflow paths for liquid entrapped in the interstices between wet masses of thickened solids. The elongated boot 35A separates the clarifyin juice receiving upper portion of the compartment F from the central flow path for the solids and liquid mixture entering compartment F from compartment EA. The eflective utilization of the compartment EA as a thickening compartment requires the clarified juice outlet pipe 58 from the compartment E to discharge at a level higher relative to the discharge level of the outlet pipe forthe-compartment EA, than would be required if the compartment .EA were not used as a thickening compartment and discharged mud of lower density.

While I now consider the clarifier shown in Figs. l and 3 to be generally preferable, at least for most uses, to the clarifier shown in Fig. 4, the last mentioned clarifier gives the same general Q advantages as the clarifier first described. of increasing the mud thickening and removal capacity of the clarifier relative to its sedimentation capacity, and thereby increases the overall discharged from the compart- As shown tube ill also supports the to the tank bottom wall II and thus provides a lower guide bearing 7 of the ciarifiers shown in not due to the diflerences in the mud thickeningclarii'ying capacity of the clarifier.

b As will be apparent to those skilled in the art, changes may be made in the form of the apparatus described without departing from 'the spirit of the invention as set forth in the appended claims. In this connection, we note that some differences in construction between the Figs. 2 and 4, are-obviously and removal provisions of the two clariflers. For

bottom compartment oi the dependingjboot 25A from that tray which surrounds the central advantageously as it is shown is appreciably longboots 2.5 carried by in-mud level height or- -;ably high relative to the clarifying loads on thecompartment is unduly fact thatthe clarifying opening in the tray and 42 in conjunction with the a mud sealed overflow nular flange 34, between the compartments A and B of Fig. 2 might be used between the compartments A and B of the clarifler shown in Fig. 4, in which case the central column body22A would be provided with teed ports like the ports 33 of 2. Moreover, the general operation of the clarifier shown in Fig. 2 would not be modifled ii theseal flange. and ports 32 were omitted, and the compartments A and B 0! Fig. 2

the compartments A and B of Fig. 4.

Having now'described my invention, what 1 claim asnew and desire to secure exit is:

1. In clarifying liquid in a multitray clarifler comprising a plurality oi superposed compartwere connected by'an annular flow path as are by Letters Fatthickening chambers from the clariflerat rate: regulable to maintain the desired thickening ac-' last mentioned chambers being located above one at least of said thickening chambers, the method which consists in passing liquid to into each of said chambers and separatelywithdrawing clarified liquid from the different chambers, passing mud from each preliminary sedimentation chamber-to a subjacent thickening chamber at a-rate rapid enough to avoid impairment of the-clarifying capacity of said preliminary sedimentation, chamber, said mud comprising a solids content including the solids from the clarified liquid withdrawn from said preliminary sedimentation chamber and comprising a liquid content constituting a portion at least of the liquid passed into said preliminary sedimentation chamber to be clarified therein, and subjecting the mud in the thickening chamber to a regulated mud thickening action by withdrawing mud from said thickening chamber at a regulated rate slow enough to maintain the mud thickening condition in said mud thickening chamber required for the desired'mud thickening action.

' 2. In clarifying liquid in a multitray clarifier comprising a plurality of supe pqsed compartments, of which the lower one and one at a higher level serve as thickening chambers and others between and above said thickening chambers serve. as preliminary sedimentation chambers, the method which consists in passing'liquid to be clarified into each of said chambers and sepa-' rately withdrawing clarified liquid from the different chambers, passing mud from each preliminary sedimentation chamber to a subjacent thickening chamber at a rate rapid enough to avoid impairment of the clarifying capacity of said preliminary sedimentation chamber, said mud comprising a solids content including the solids separated from the clarified liquid withdrawn from said preliminarysedimentation chamber and comprising a liquid content constituting a portion at least of the liquid passed into I said preliminary sedimentation chamber to be clarified therein, and subjecting the mud in each thickening chamber to a regulated mud thickening action by separately withdrawingmud from the different thickening compartments at regulated rates each suitably small to maintain the mud thickening condition in the corresponding mud thickening chamber required for the desired mud thickening action therein. v

3. A multitray clarifier comprising a tank and partitions therein separating a plurality of superposed compartments two-or more of which serve as thickening chambers and the others of which serve as preliminary sedimentation chambers, feeding means including a separate feed inlet to each preliminary sedimentation chamber for passing liquid to be clarified into each of said chambers, a separate conduit connection to each chamber for the outflow therefrom of clarified liquid, means for moving mud from each preliminary sedimentation chamber into a subiacent thickening chamber at a rate rapid enough to avoid impairment of the clarifying capacity of said preliminary sedimentation chamber, said mud comprising a solids constituent including the solids separated in the last mentioned chamber from the liquid clarified therein and comprising a liquid constituent constituting a portion at least of the liquid fed into said preliminary sedimentation chamber for clarification therein and means tion.

4. A multitray clarifier as specified in claim 3 having a preliminary sedimentation chamber interposed between two thickening compartments and comprising separate ofi take conduit connections to said two thickening chambers through which solids thickened therein are separately re moved from the clarifier.

5. A multitray clarifier as specified in claim 3 inwhich the lowermost compartment and the compartment immediately above it serve as thickening chambers and which comprises means for passing thickened solids into the lowermost compartment from the thickening chamber immediately above it and comprises an elf take connection to the lowermost compartment for the discharge of thickened solids from the clarifier.

6. A multitray clarifier as specified in claim 3 in which each of said partitions-is formed with a central aperture and which comprises a rotatable'structure including a central column portion extending through said central tray apertures and to said two thickening chambers through which solids thickened therein are separately removed from the clarifier and in which the partition separating the upper thickening chamber and the preliminary sedimentation chamber interposed between the thickening chambers is formed with a central opening and an upcast boot carried by said partition and surrounding said opening whereby solids accumulating in the upper thick-' ening chamber mayoverfiow through said open- .ing into the subjacent chamber.

8. A multitray clarifier as specified in claim 3 having a preliminary sedimentation chamber interposed between two thickening chambers and comprising separate 01! take conduit connections to said two thickening chambers through which solids thickened therein are separately removed from the clarifier and in which the partition separating the upper thickening chamber and the preliminary sedimentation chamber interposed between the thickening chambers is formed with a central opening and an upcast boot carried by said partition and surrounding said opening, and means including a part surrounding the upper portion of said boot which unite with the latter and with said central opening to form a mud sealed overflow outletfrom the upper thickening chamber into the subjacent chamber. 9. In a'multitray clarifier comprising a tank and partitions therein separating a plurality of.

A superposed compartments, aseparate conduit for subjecting the mud in said thickeningchamconnection to each of said com artments for the outflow of clarified liquid, feeding means including a separate feed inlet to each of said compart ments for passing liquid to. be clarified thereinto, means for withdrawing mud from the clarifier inbinding .a mud withdrawal conduit connection to a means comprising an 6 compartment located above the iowermost'compartment and serving as a mud thickening chamher and a separate mud withdrawal conduit-concrease in. the mud accumulation in said thickening chamber. 7 10. A multitray clariiler comprising a tank and partitions therein separating a plurality of superfrom the liquid in the I solids thickened therein at extent to which the solids are thickened in said 2,e4s,ssc

posed compartments, aplurality of which serve as thickening chambers and other of which serve as clarifying chambers, means feeding liquid to the clarifler to be clarified therein, means for distributing said liquid to be'clarifled to the different compartments, a separate conduit connection to each compartment for the outflow oi! clarifled liquid; means for clari y chambers into and means for withthickening chambers the thickening chambers, drawing from each of the thickening chamber.

' 11, A multitray clarifier as'specifled in claim 3,

including mechanical thickening elements in each thickening chamber and means for rotating said WILLIAM CI WEBER.

elements.

passing solids separating a rate regulating the- 

